1. Field of the Invention
This invention relates to plugs used in friction pull plug welding. More specifically, the invention is friction pull plug whose lateral surfaces are configured to reduce or eliminate chatter when the plug contacts a material's hole during a friction pull plug welding process.
2. Description of the Related Art
Friction pull plug welding involves locating a defective weld, removing the defect to form a hole in a material, and filling the hole with a tapered plug that is friction welded into place. In general, a friction pull plug is rotated at high speeds, e.g., typically several thousand revolutions per minute. As the rotating plug comes into contact with a material's hole that is to be plugged, tremendous torque and loads are required to maintain the rotational speed of the plug. Any chatter developed during this stage of the process can produce torque that stalls the machine rotating the plug or causes speed fluctuations that can cause variations in the weld's strength. These problems are exacerbated when a plug's taper angle is decreased as is generally the case with increasing material thickness.